Chapter 43: The Nervous System Flashcards
Central Nervous System
information processing system (CNS)
brain and spinal cord
Peripheral Nervous system
PNS
includes the afferent division, and efferent division (which splits into somatic and autonomic nervous systems)
Afferent division
Part of PNS
transmits sensory info; can determine significance of info after processing
Example: seeing colors, sensing motion in hair
Efferent division
Part of PNS
transmits motor info
includes the somatic and autonomic (parasympathetic and sympathetic) systems
Somatic nervous system
made up of motor and sensory neurons
includes voluntary movement and control
Autonomic nervous system
includes involuntary movement (adrenaline, dilated pupils, and heart racing)
parasympathetic and sympathetic systems
Parasympathetic
rest and digest response
slow heart rate, constrict pupils, stimulate salivation, stomach and intestine activity, contract bladder, inhibit release of glucose from liver
Sympathetic
fight or flight response
heart racing, pupils dilated, relax bladder, inhibit stomach and intestine activity, secrete epinephrine and norepinephrine from adrenal glands
Neurons
fundamental parts of the brain and nervous system, recieve sensory inputs from external world
dendrites
convert chemical signals to electrical signals
Chemical, sound based, light etc
cell body
where dendrites are attached to; integrates incoming electrical signals(what do to with them); If significant enough, sends signal down axon
Axon
conducts electrical signals
Can be quite a long length!
three main types of neurons in nervous system
sensory neurons, interneurons, and motor neurons
Sensory neurons
These are specialized neurons that are responsible for detecting sensory stimuli from the environment and transmitting this information to the central nervous system.
Sensory neurons have specialized receptor cells that respond to different types of stimuli such as light, sound, touch, temperature, and chemicals.
They are located in sensory organs such as the eyes, ears, nose, tongue, skin, and internal organs.
Interneurons
Interneurons are located in the spinal cord and brain and act as intermediaries between sensory neurons and motor neurons. They integrate and process the information received from sensory neurons and transmit signals to motor neurons or other interneurons. Interneurons are responsible for many of the complex functions of the nervous system such as perception, memory, learning, and decision-making.
Motor Neurons
These neurons are responsible for transmitting signals from the brain and spinal cord to the muscles and glands, allowing for movement and secretion. Motor neurons are divided into two types: somatic motor neurons, which control voluntary movement of skeletal muscles, and autonomic motor neurons, which control involuntary movement of smooth muscles, cardiac muscles, and glands.
How does information flow in neurons?
dendrites (convert chemical signals to electrical signals) -> cell body (integrates incoming electrical signals ) -> axon (conducts electrical signals)
Myelin Sheath
insulation of axon
Made up of Schwann Cells and Oligodendrocytes
Immune system (neurons)
Microglia are primary caretakers
Astrocytes help
Blood brain barrier
controls what gets in and out of nervous system
Astrocytes can do this
Resting membrane/membrane potential
electrical potential difference across a biological membrane
o Created by separation of charged ions across the membrane; more positive ions on one side and more negative ions on the other side
o Difference in charge creates voltage gradient, measured in millivolts (mV)
Contributors to membrane potential
Na/K pump
intracellular proteins
K leak channels
Na/K pump
pushing out Na+, kicking in K+
* Does not affect -70mv (resting potential) until change happens with some other contributors
Intracellular proteins
K leak channels
strongest contributor to membrane potential! Puts in motion of change with other contributors; allows K+ to diffuse in and out
3 main changes to membrane potential
polarization, depolarization, and hyperpolarization
repolarization involved in some ways
Polarization
refers to the state of the membrane potential when there is a separation of charge across the membrane, resulting in voltage difference between inside and outside the cell
Can happen when inside of the cell is negatively charged relative to the outside
Depolarization
often referred to as excitatory stimulus
o Membrane potential becomes less polarized; voltage difference across membrane is smaller
o Occurs when positively charged ions enter the cell or negatively charged ions exit the cell
o KEY STEP in generation of action potentials
Hyperpolarization
often referred to as inhibition
o Membrane potential becomes more polarized, voltage difference across membrane becomes larger
o Negatively charged ions enter the cell or positively charged ions exit the cell
o Harder to create an action potential, is increasing difference the action potential must overcome
Repolarization
involves multiple excitatory events that cause greater depolarization (can lead to action potentials)
Graded potentials
Driven by opening and closing of ligand-gated ion channels
When a ligan (acetylcholine) binds a receptor, a sodium channels is opened
* Membrane will then experience small, brief depolarization
Give a summary of the ability of graded potentials to combine
1) Depolarization: often referred to as excitatory stimulus
2) Multiple excitatory events cause greater depolarization
3) Hyperpolarization: often referred to as inhibition
* 4) summarization/summation of 1, 2, and 3
* ** If enough summarization/summation occurs, you can produce action potentials!
